Because of the world's limited land and food resources, there has been an ever growing interest in increasing the yield of food-bearing plants. As sugar is among the principal foods for man and animals, as well as a commercially important food for fermentation organisms, it is only natural that much effort continues to be devoted to increasing the sucrose yield of sugarcane in a variety of ways, such as by improvement of the varieties of cane being planted, by enrichment of the soil with fertilizers and by irrigation where natural moisture was insufficient for optimum plant growth. In the past decade or two scientists seeking to increase sugar production have increasingly investigated the use of a variety of chemicals in efforts to modify and control the physiological processes of sugarcane, particularly its ripening prior to harvest.
Some of the more successful prior efforts are disclosed in U.S. Pat. Nos. 3,224,865; 3,245,775; 3,291,592; 3,482,959; 3,482,961; 3,493,361; 3,505,056; 3,660,072 and 3,671,219. However, failures continue to outnumber successes by a wide margin and a dependable rule for predicting utility of a given compound or chemical structure continues to elude those working in this art. Because of concern about the resistance of some compounds to breakdown in the plant and their persistence in the soil, their deliberate application to sugarcane has generally been viewed with misgivings pending proof of their non-toxicity, unless the intended use of the sugar product is industrial, e.g., in a fermentation process, rather than nutritive. Accordingly, the search for new sugarcane ripeners continues unabated.
Generally speaking, chemicals selected for evaluation have been of a type which has been previously found active in work with other plants as a plant hormone, herbicide or inhibitor of growth of terminal buds, or active in killing the spindle of cane upon topical microapplication, etc. However, among the compounds heretofore known to be useful for such other special purposes only a few are found to be effective in controlling the ripening of sugarcane in the desirable manner. No predictable relationship has yet been recognized between (a) the chemical structure of such compounds, (b) their phytotoxic effects, or (c) their physiological effects on the morphogenetic development of the plant, on the one hand, and their activity in having positive effects on ripening, on the other hand. In other words, the effectiveness of a compound in controlling the ripening of sugarcane and thereby increasing sugar yield remains essentially unpredictable, and the search for suitable chemical ripeners continues to be fundamentally empirical.